This invention pertains to cooled mirrors, and more particularly to cooled mirrors wherein the frontplate and backplate, with integral heat exchangers are of one material and the mirror substrate is of another material.
As the power in radiation beams has increased so too has the need to cool the mirrors used to redirect such high powered beams. Past solutions to the problem are ineffective for new systems with more stringent requirements or caused further problems of their own.
One approach has been to construct a mirror with an integral heat exchanger or with an attached heat exchanger of the same material as the mirror substrate. Such materials do not meet the simultaneous requirements for high conductivity in the heat exchanger and low thermal expansion in the substrate.
Another approach is to provide a heat exchanger on the active side of the mirror which is highly thermally, conductive but of a different material than the substrate. This provides a heat exchanger that can accommodate the high thermal loads. The drawback to this approach is the bimaterial effect caused by joining the two materials with different thermal coefficients of expansion. The different thermal coefficients of expansion of the two materials cause the assembly to bend when the ambient temperature changes.
In the cooled mirror disclosed in the present application the disadvantages of the prior art cooled mirrors are overcome by providing a novel heat exchanger configuration which both carries away unwanted heat produced by high power radiation and also compensates for the bimaterial bending encountered in other approaches.